Even though this is probably low quality bait and I should respond sarcastically, just in case you're serious, I'll answer sincerely.
Not everyone has access to original hardware, and in some cases, older games can be very expensive (see Little Samson where a cart can run you $1000 or more unless you are lucky enough to find a repro, but even thats not cheap). Or DS games where a DS capture card is hundreds of dollars. The price to run some games can be quite expensive and can make it impossible to require nothing but real hardware while having competition of some kind. So, emulation is allowed to make it easier for people to run those games.
Another reason it's allowed is that for older consoles (N64 and prior, although even N64 is pushing it) is that the emulators are extremely accurate because of how outdated the actual hardware is. This makes it easy to emulate older consoles with great accuracy so that from a functional/loading perspective, neither emulator or hardware gives you an unfair advantage; all that might change is some input lag but that can be adjusted to. For newer systems like PS2, Wii/GC, etc. emulation is almost always banned because those emulators tend to run/load faster and have less lag than original hardware. Since that is an unfair advantage and can be even more drastic depending on your PC specs, those emulators are not allowed.
In short, emulation for older games is allowed because there are emulators for those consoles that are very accurate and don't offer any unfair advantage over real hardware. Emulation for newer consoles does not tend to get the same treatment because it can make games run faster than they are supposed to which will result in them either being banned or separated from the real console so as not to have unfair advantages.
Don't be so quick to judge. You can't post without an account, yeah? How else are you supposed to ask something here? There's not exactly an FAQ yet, and things that may seem obvious to you aren't necessarily obvious to everyone.
The same thing happened to me when I first joined. I just wanted to know what was considered tool assisted and what wasn't, and it got a bit out of hand: https://www.speedrun.com/Speedrunning/thread/n1u5f
Emulation is better than real machine so we reject all emulated runs, why not have a separate category for emulated runs instead of banning them altogether? Seems like a big fuck you if you have a decent computer that runs the emulator faster than me.
It's not a big fuck you, its fairness and consistency.
If computer hardware makes an emulator run faster then you're basically saying "spend $2000 to be competitive in this game" which is just unfair to do and will stifle competition. This is the biggest thing that drives PS2 era and later games to often ban emulators.
Some games do have emulator only categories (I think some of the PS2 FF games do), but that is a case by case basis and depends on the demand for it. Other games just ban them because they are inconsistent even with a strong computer and anything that can have that much variance in performance doesn't make sense to allow.
In portable consoles, the emulators are usually allowed, as they have no advantages in terms of loading times to play on a real console. On the desktop some PS1/NES/SNES titles are also usually allowed to use, but more recents systems like PS2 / Wii / GC / PS Usually are banned the use of emulators, in some cases until USB/SD loaders because of those methods tend to run / load faster and have less lag than the original hardware. Let's also take into account that the video capture devices in the portable consoles usually have a very high cost, hundreds of dollars only for saying "to be competitive in this game". It is a rather high cost and that not all speedrunners are going to obtain, not easily.
Imagine someone responding to your post with an unrelated jab at your slight grammar error in your second language
Imagine someone registered on this website to ask a troll question.
Imagine someone facepalming when they realize the comment was targeted at the very first post and not the one preceding it.
Because that's me right now irl
